✓ The authors investigated the efficacy of anal sphincter electromyography (EMG) in identifying the lower sacral roots during selective dorsal rhizotomy. In nine children undergoing selective dorsal rhizotomy for cerebral palsy (CP) spasticity, direct electrical stimulation of the L1—S5 dorsal and ventral roots was performed while monitoring EMG responses from the anal sphincter and lower-extremity muscles. Anal sphincter activation was seen with stimulation of lumbosacral roots at many levels. Stimulation of dorsal and ventral roots gave anal sphincter EMG responses in 100% of the dorsal and ventral roots from L-4 and caudally. Only at the L-1 level did a minority of nerve roots have anal sphincter response to stimulation. Patterns of extremity muscle and sphincter activation specific to the S3–5 roots, namely anal sphincter activation without activation of other muscle groups, were found in only five (22%) of 23 roots stimulated. The pattern of stimulation responses in the majority of S3–5 roots indicated that the pathophysiology of lower-extremity spasticity in CP may involve the anal sphincter and does not spare the lower sacral roots. Thus, this study indicates that electrophysiological mapping alone, without anatomical identification, cannot be used to identify the lower sacral roots during selective dorsal rhizotomy for CP spasticity, and it proposes a model for investigation of associated bowel and bladder symptoms.
Jeffrey G. Ojemann, T. S. Park, Robert Komanetsky, Richard A. A. Day, and Bruce A. Kaufman
Jeffrey G. Ojemann, Robert L. Grubb, Michael Kyriakos, and Kim B. Baker
✓ This 52-year-old woman developed crystal deposition disease involving the cervical vertebrae. She presented with symptomatic spinal cord compression secondary to extensive calcified lesions in the posterior elements of the cervical spine. Surgical decompression with posterior fusion was performed. Histological examination showed hardened deposits of calcium carbonate involving the soft tissue, and dissolution of the vertebral bone trabeculae. There was no inflammatory response to these deposits. One year postoperatively the patient developed severe pulmonary disease associated with the collagen-vascular disorder, scleroderma (calcinosis, Raynaud's phenomenon, esophageal hypomotility, sclerodactyly, and telangiectasia [CREST] syndrome). Calcium carbonate deposition disease represents an unusual clinical entity that is possibly associated with scleroderma or other collagen-vascular diseases, and it is distinct from ligamentum flavum calcification, calcium pyrophosphate deposition disease, and hydroxyapatite deposition disease.
Report of two cases
Jeffrey G. Ojemann, Christopher J. Moran, Murat Gokden, and Ralph G. Dacey Jr.
✓ Lesions involving the sagittal sinus typically present as masses compressing the sinus externally. The authors describe two cases of lesions entirely within the lumen of the sagittal sinus. In one of the cases, syncope was the presenting symptom and surgical resection of the cyst was performed. An entirely intraluminal cyst, consistent with a dural cyst, was resected, followed by reconstruction of the sinus and resolution of symptoms. Entirely intraluminal lesions of the sagittal sinus have rarely been reported as incidental findings. This represents the first report of symptomatic occlusion of a venous sinus by an intraluminal cyst.
Tord D. Alden, Jeffrey G. Ojemann, and T. S. Park
Chiari I malformation is a well-described entity characterized by hindbrain herniation through the foramen magnum. Although the exact origin of congenital Chiari I malformation is unknown, it appears to be caused by a mismatch between the volume of the posterior fossa neural elements and the posterior fossa cranial content. Several theories have been proposed to describe the resultant pathophysiology of this mismatch. It is clear, however, that abnormal cerebrospinal fluid flow and velocity play a role in the symptoms and signs associated with this disorder. The authors will review the pathophysiology, clinical presentation, and treatment options for patients with Chiari I malformation.
Jeffrey G. Ojemann, George A. Ojemann, and Ettore Lettich
Object. Cortical stimulation mapping has traditionally relied on disruption of object naming to define essential language areas. In this study, the authors reviewed the use of a different language task, verb generation, in mapping language. This task has greater use in brain imaging studies and may be used to test aspects of language different from those of object naming.
Methods. In 14 patients, cortical stimulation mapping performed using a verb generation task provided a map of language areas in the frontal and temporoparietal cortices. These verb generation maps often overlapped object naming ones and, in many patients, different areas of cortex were found to be involved in the two functions. In three patients, stimulation mapping was performed during the initial performance of the verb generation task and also during learned performance of the task. Parallel to findings of published neuroimaging studies, a larger area of stimulated cortex led to disruption of verb generation in response to stimulation during novel task performance than during learned performance.
Conclusions. Results of cortical stimulation mapping closely resemble those of functional neuroimaging when both implement the verb generation task. The precise map of the temporoparietal language cortex depends on the task used for mapping.
William W. Ashley Jr., Jeffrey G. Ojemann, Tae Sung Park, and Franz J. Wippold II
✓The authors report on a 12-year-old girl with a suprasellar mass and primary hypothyroidism in whom the lesion promptly regressed following initiation of thyroid replacement therapy. Based on this experience, it is suggested that secondary pituitary hyperplasia be included in the differential diagnostic considerations of a suprasellar lesion in a child and that resolution of the hyperplasia may occur in a matter of weeks rather than months as previously reported.
James M. Johnston Jr., Francesco T. Mangano, Jeffrey G. Ojemann, Tae Sung Park, Edwin Trevathan, and Matthew D. Smyth
The purpose of this study was to better define the incidence of complications associated with placement of subdural electrodes for localization of seizure foci and functional mapping in children.
The authors retrospectively reviewed the records of 112 consecutive patients (53 boys, 59 girls; mean age 10.9 years, range 10 months–21.7 years) with medically intractable epilepsy who underwent invasive monitoring at the Pediatric Epilepsy Center at St. Louis Children’s Hospital between January 1994 and July 2005. There were 122 implantation procedures (85 grids and strips, 32 strips only, five grids only, four with additional depth electrodes), with a mean monitoring period of 7.1 days (range 2–21 days). Operative complications included the need for repeated surgery for additional electrode placement (5.7%); wound infection (2.4%); cerebrospinal fluid leak (1.6%); and subdural hematoma, symptomatic pneumocephalus, bone flap osteomyelitis, and strip electrode fracture requiring operative retrieval (one patient [0.8%] each). There were four cases of transient neurological deficit (3.3%) and no permanent deficit or death associated with invasive monitoring.
Placement of subdural grid and strip electrodes for invasive video electroencephalographic monitoring is generally well tolerated in the pediatric population. The authors found that aggressive initial electrode coverage was not associated with higher rates of blood transfusion or perioperative complications, and reduced the frequency of repeated operations for placement of supplemental electrodes.
Matthew D. Smyth, David D. Limbrick Jr., Jeffrey G. Ojemann, John Zempel, Shenandoah Robinson, Donncha F. O'Brien, Russell P. Saneto, Monisha Goyal, Richard E. Appleton, Francesco T. Mangano, and Tae Sung Park
The authors conducted a multiinstitutional, retrospective analysis to better define outcome and prognostic indicators for temporal lobe epilepsy surgery for suspected mesial temporal sclerosis (MTS) in young children.
Data were collected for all children undergoing temporal resections at four epilepsy centers over approximately 10 years. Children with a histopathological diagnosis of neoplasm were excluded.
Forty-nine patients (28 boys and 21 girls) were included in the study. Their mean age at surgery was 9.1 years (range 1.25–13.9 years). The mean age at seizure onset was 3.2 years (range birth–10 years). Histopathological examination demonstrated MTS in 26 cases, gliosis in nine, dysplasia in five, gliosis with dysplasia in four, and nonspecific or normal findings in five. Forty-one anterior temporal lobectomies (nine tailored) and eight selective amygdalohippocampectomies were performed (28 left side, 21 right side). Twenty-nine children (59.2%) underwent invasive monitoring. Operative complications included extraaxial hematomas (two cases), cerebrospinal fluid leaks (two cases), and hydrocephalus (one case), each in children undergoing invasive monitoring. The mean duration of follow up was 26.4 months (range 5–74 months) overall and 23.9 months (range 6–74 months) for the Engel Class I subgroup. Outcomes at the most recent follow-up examination were categorized as Engel Class I–II in 31 (63.3%) of 49 children overall, 20 (76.9%) of 26 children with confirmed MTS, four (36.4%) of 11 children with gliosis, and four (57.1%) of seven children with dysplasia. All patients who underwent selective amygdalohippocampectomies had confirmed MTS and Engel Class I outcomes. Patients with more than one seizure type (p = 0.048) or moderate to severe developmental delay (p = 0.03) had significantly worse outcomes (Engel Class III or IV). Age at seizure onset, age at surgery, and duration of seizure disorder were not significantly related to outcome. There was a trend for bilateral or extratemporal findings on electroencephalography (EEG) (p = 0.157), high preoperative seizure frequency (p = 0.097), and magnetic resonance (MR) imaging findings inconsistent with MTS (p = 0.142) to be associated with worse outcome, although it did not reach statistical significance. In only 12 (46.1%) of the 26 patients with confirmed MTS was the condition prospectively diagnosed on preoperative MR imaging.
Younger children with temporal lobe epilepsy have satisfying surgical outcomes, particularly when MTS is present. Magnetic resonance imaging may not be as sensitive in detecting MTS in children as in older patients. Negative predictors identified include multiple seizure types and preoperative developmental delay. Multifocal or bilateral EEG findings, high preoperative seizure frequency, and MR imaging findings inconsistent with MTS also independently suggested worse outcome.
Reinhold Scherer, Stavros P. Zanos, Kai J. Miller, Rajesh P. N. Rao, and Jeffrey G. Ojemann
Electrocorticography (ECoG) offers a powerful and versatile platform for developing brain-computer interfaces; it avoids the risks of brain-invasive methods such as intracortical implants while providing significantly higher signal-to-noise ratio than noninvasive techniques such as electroencephalography. The authors demonstrate that both contra- and ipsilateral finger movements can be discriminated from ECoG signals recorded from a single brain hemisphere. The ECoG activation patterns over sensorimotor areas for contra- and ipsilateral movements were found to overlap to a large degree in the recorded hemisphere. Ipsilateral movements, however, produced less pronounced activity compared with contralateral movements. The authors also found that single-trial classification of movements could be improved by selecting patient-specific frequency components in high-frequency bands (> 50 Hz). Their discovery that ipsilateral hand movements can be discriminated from ECoG signals from a single hemisphere has important implications for neurorehabilitation, suggesting in particular the possibility of regaining ipsilateral movement control using signals from an intact hemisphere after damage to the other hemisphere.